text: In addition to his isolation and study of germanium, Winkler investigated the analysis of gases.  He published a book on the subject, Handbook of Technical Gas Analysis, in 1884.  In that book Winkler describes his invention of the three-way stopcock. He predicted the existence of silicon monoxide, SiO, and was the first to attempt to produce it by heating silica with silicon in 1890.  However, he was unsuccessful because he was not able to heat the mixture to a high enough temperature using a combustion furnace.  As no reaction occurred for him, Winkler incorrectly concluded that SiO does not exist, even though it was reported to have formed from the reduction of silica with charcoal three years earlier by C. F. Maybery.  However, Henry Noel Potter, a Westinghouse engineer, repeated Winkler's experiment fifteen years later with an electric furnace, which enabled him to increase the reaction temperature by several hundred degrees and observe the generation of SiO.